Method and device for cleaning a dirty surface

ABSTRACT

A method and a device_for cleaning a dirty surface, wherein water is squirted from a nozzle against the dirty surface in order to wash away the dirt with the water, characterized in that compressed air is supplied to the water in a mixing chamber, which is located upstream of the nozzle, at a predetermined pressure, after which the water is squirted against the dirty surface in a spray of droplets, downstream of the nozzle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent application Ser. No. 09/299,109, filed Apr. 26, 1999, which is a continuation application of co-pending International Application No. PCT/NL97/00566, filed Oct. 10, 1997, designating the United States of America, which International Application claims priority to Netherlands application no. NL 1004462, filed on Oct. 24, 1996, and to Netherlands application no. NL 1006604, filed on Jul. 17, 1997. All of the above referenced patent applications are herein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for cleaning a dirty surface, wherein water is squirted from a nozzle against the dirty surface in order to wash away the dirt with the water.

2. Description of the Related Art

Such a method is generally known. With the known method water is forcefully squirted from the nozzle onto the dirty surface, whereby the dirt is washed away from the surface with the water and a cleaned surface is obtained.

One drawback of the known method is that apart from the fact that a relatively large amount of water is needed to achieve an adequate cleaning effect, that statutory regulations in a growing number of countries furthermore forbid the discharge of the washed-away water, which is contaminated with dirt, into the surface water. This drawback will be explained in more detail by means of the example below. Consumer demands force growers to present their crops to the retail trade in clean condition, that is, looking attractive. For the average Dutch leek grower this meant in 1996 that as many as 30,000 litres of pure water had to be used per hour to wash leek adequately. Now that pure water is becoming increasingly rare and consequently more expensive these days, such quantities of used-up water are unacceptable, also from a social point of view. Leek growers are legally prohibited from discharging the water contaminated with dirt from the leek into the surface water just like that, however, so that the grower is obliged to take additional measures for purifying the washing water. Usually the so-called “basin method” is used thereby, the washing water contaminated with earth is allowed to settle in a basin, as a result of which the earth can deposit on the bottom of the basin and the water in the upper portions of the basin will become relatively pure. Taking into account the above-mentioned amounts of water required for cleaning leek, huge basins are needed in practice, also because the sedimentation process typical of the “basin method” proceeds very slowly. It will be apparent that the industry in general is faced on the one hand with the need to supply clean products in order to meet consumer requirements, and on the other hand with the need to use less and less (tap) water, whereby washing water is only discharged into the surface water after being purified. In spite of the industry's long-felt need to find an adequate solution for this dilemma, nobody has succeeded in doing so up to now.

SUMMARY OF THE INVENTION

The object of the invention is to provide a method for cleaning a dirty surface, wherein the drawbacks of the prior art are overcome in a simple yet efficient manner, that is, that considerably less water is required for cleaning a dirty surface, without this having an adverse effect on the cleaning result.

In order to accomplish that objective a method of the kind referred to in the introduction is according to the invention characterized in that compressed air is supplied to the water in a mixing chamber, which is upstream of the nozzle, at a predetermined pressure, after which the water is squirted against the dirty surface in a spray of droplets, downstream of the nozzle. Extensive research has surprisingly shown that when the water is mixed with the pressurized air in the mixing chamber, it becomes possible to squirt the water in a spray of droplets against the dirty surface downstream of the nozzle. A very great cleaning effect is achieved with the mixture of water and compressed air exiting the nozzle and the fine water droplets thus produced. Furthermore the water droplets hitting the dirty surface appear to wash away the dirt and thus produce a cleaning effect, whilst the force at which the spray of water droplets is squirted onto the dirty surface appears to be so small in practice, that the surface is not damaged. The velocity at which the water droplets, which have a particular mass, are being moved is effected by the compressed air, as it were, which results in an optimum impetus of the water droplets. Compared with the known method, the method according to the invention appears to provide a water saving of more than 95%, which in the above-discussed example of the washing of leek boils down to an amount of 300 litres of water per hour being used up compared with the 30,000 litres of water per hour that were used previously. This means a saving of as much as 237,600 litres of water per eight hours. It is noted that the invention has a very wide range of applications, as will be explained in more detail yet, wherein in particular bulb growing, fruit and vegetable growing, shower cubicles, carwashes, dishwashers and washing machines, industrial washing plants and machine cleaning plants may be considered.

International patent publication No. WO 96/33817 (Lawrence) describes a suds generator, wherein water under high pressure is supplied to a mixing chamber in a high-pressure mode, and is subsequently discharged via a discharge pipe and a high-pressure spray nozzle. Water and a soap solution under low pressure are supplied to the mixing chamber in a low-pressure mode, whilst air under high pressure is carried to the aqueous soap solution present in the mixing chamber through a perforated pipe. As a result of this suds are produced in the mixing chamber, which suds leave said mixing chamber via the discharge pipe and a low-pressure nozzle.

In one preferred embodiment of a method according to the invention the air pressure is at least 1 bar, preferably at least 1.5 bar. More in particular the air pressure can be regulated, preferably even steplessly so. A finely divided spray of water droplets is obtained by mixing the water with the thus pressurized air in the mixing chamber, whereby the consumption of water is minimized in an optimum manner without affecting the cleaning result.

In another preferred embodiment of the method according to the invention pressurized water is supplied to the mixing chamber at a predetermined pressure, downstream of the nozzle, whereby the water pressure can be regulated, preferably steplessly so. This makes it possible to adapt the shape and the size of the droplets and the water/air ratio to the conditions of the surface to be cleaned. Ideally the water pressure can be regulated independently of the air pressure.

In another preferred embodiment of a method according to the invention the air pressure and the water pressure are set to a ratio ranging between 21 and 12.

In another preferred embodiment of a method according to the invention the water is squirted against the surface in a spray of droplets, from a distance which is smaller than the distance at which the water becomes turbulent downstream of the nozzle. It has become apparent that the spray of droplets becomes turbulent at a particular distance from the nozzle, whereby there is no longer a water jet, but whereby the water droplets “float” as it were. In that case the water droplets no longer have an “impetus”, as a result of which they are hardly able to remove dirt from the surface.

The invention also relates to a device for carrying out a method according to the invention, which is characterized in that it comprises a mixing chamber, at least one nozzle connected thereto, as well as means for supplying water, which may or may not be pressurized, and compressed air at a predetermined pressure, to the mixing chamber, which is upstream of the nozzle. More in particular the nozzle is present in a wall of the mixing chamber thereby, which mixing chamber preferably converges in the direction of the nozzle. The advantage of this is that the spray of fine water droplets is capable of exiting the nozzle at great force, whilst furthermore an optimum mixing of water and pressurized air is effected.

In one preferred embodiment of a device according to the invention means are provided for regulating the air pressure, preferably steplessly so, as well as means for regulating the water pressure, preferably steplessly so, in particular independently of the air pressure.

In another preferred embodiment of a device according to the invention the nozzle is movable, preferably the nozzle is mounted on a rotatable arm. This makes it possible to further reduce the distance between the nozzle and the surface to be cleaned, as a result of which the discharge of the dirt is further improved.

In another preferred embodiment of a device according to the invention the mixing chamber comprises a member which is capable of rotation under the influence of the water for rotatably squirting the water in a spray of droplets downstream of the nozzle. The rotating spray of water droplets results in an enlarged working area. Preferably the device is accommodated in a housing. This makes it possible to use a closed system, wherein used up water may be caught and the surrounding area cannot be contaminated by a spray of water droplets. The recirculation of used water is an advantage per se, because less water is needed.

The invention also relates to a method and a device for cleaning flower bulbs, flower tubers or perennial plant(s) (parts), wherein the water pressure and the air pressure are set in accordance with claim 9.

The invention furthermore relates to a method and a device for cleaning soft fruit, in particular strawberries, grapes, plums, red currants, blueberries or peaches, according to any one of the preceding claims 1-8, wherein the water pressure and the air pressure are set in accordance with claim 10

The invention also relates to a method and a device for cleaning medium hard crops, in particular leek, asparagus, beans, stone leeks, paprikas, gherkins, cucumbers, cabbage varieties (cauliflower, white cabbage, green cabbage, red cabbage, etc.) or tomatoes, wherein the water pressure and the air pressure are set in accordance with claim 11.

The invention also relates to a method and a device for cleaning hard crops, in particular carrots, scorzoneras and rootstocks and/or fruit trees, stem crops and/or root crops for multiplication purposes, products stemming from the cultivation of onions and/or silver-skin onions or carrots, wherein the water pressure and the air pressure are set, in accordance with claim 12.

The invention also relates to a method and a device for cleaning sugar beets, beetroots or potatoes, or the products stemming therefrom, in particular chips, pulp and cattle fodder products, wherein the water pressure and the air pressure are set in accordance with claim 13.

The invention also relates to a method and a device for cleaning roads, in particular porous asphalt, wherein the water pressure and the air pressure are set in accordance with claim 14. The method and the device are excellently suited for being used for cleaning roads fouled by cadavers.

The invention also relates to a method and a device for cleaning vehicles, in particular passenger cars in a car wash, trains, buses or lorries in special washing facilities, wherein the water pressure and the air pressure are set in accordance with claim 15.

The invention also relates to a method and a device for cleaning crockery, cutlery and the like in a dishwasher, and machines or tools in an industrial washing-up machine, wherein the water pressure and the air pressure are set in accordance with claim 16.

The invention also relates to a method and a device for cleaning persons, using a shower head, wherein the water pressure and the air pressure are set in accordance with claim 17. In this connection the use of nozzles/shower heads for cleaning purposes with accidents or calamities may be considered.

The invention also relates to a method and a device for cleaning hard surfaces, in particular facades of houses, industrial and commercial buildings, glass, plastics and metal, wherein the water pressure and the air pressure are set in accordance with claim 18.

The invention also relates to a method and a device for cleaning soft surfaces, in particular wool or fibrous materials, such as cotton, flax, textile, silk or paper, wherein the water pressure and the air pressure are set in accordance with claim 19.

It is explicitly noted that the above preferred uses of a method and a device according to the invention may form the subject matter of a divisional patent application.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail hereafter with reference to Figures illustrated in a drawing, which all relate to preferred variants, wherein:

FIG. 1 is a diagrammatic sectional view of a nozzle of a device according to the invention;

FIG. 2 corresponds with FIG. 1, with the understanding that another embodiment of the nozzle is shown;

FIG. 3 is a sectional view of nozzles mounted on a rotatable arm;

FIG. 4 is a diagrammatic view of a device according to the invention;

FIG. 5 relates to a detail of FIG. 4;

FIG. 6 is a diagrammatic view of an bulb re-washing machine according to the invention;

FIG. 7 is a diagrammatic plan view of a detail of a leek washing machine according to the invention;

FIG. 8 is a side view of a detail of FIG. 7;

FIG. 9 is a diagrammatic sectional view of a carwash according to the invention;

FIG. 10 is a diagrammatic sectional view of a dishwasher according to the invention; and

FIG. 11 is a diagrammatic sectional view of a tumbler washing machine according to the invention.

DETAILED DESCRIPTION

FIG. 1 shows a spray nozzle 1, which consists of a connecting block 2 provided with an air connection 3 and a water connection 4. A nozzle housing 5 is screwed into connecting block 2. Nozzle housing 5 is provided with a water channel 6, which is in communication with water connection 4 when screwed into connecting block 2. Furthermore three air channels 7 in nozzle housing 5 connect to an annular chamber 8 in connecting block 2, which annular chamber 8 is in communication with air connection 3. A sealing ring 9 is present between connecting block 2 and nozzle housing 5. A pressure nozzle 11 is mounted on nozzle housing 5 by means of a fastening ring 10, whereby a mixing chamber 12 is formed between pressure nozzle 11 and nozzle housing 5. Pressure nozzle 11 is provided with an orifice 13.

Water is mixed with air in mixing chamber 12, with the mixture exiting via orifice 13, whereby a suitable selection of the air pressure and the water pressure causes the mixture to be atomized into fine droplets. When the air pressure is increased, the amount of water being sprayed will be reduced.

Upon testing of the spray exiting from orifice 13 in connection with the cleaning of objects, it has become apparent that the mixture of water and air, with the air being mixed with the water under high pressure, is excellently suited for cleaning objects. The dirt present on the objects comes off easily and can be washed away. During said spraying a spray of minute water droplets is formed, which droplets ensure that the dirt is penetrated everywhere and that the surface of the object is adequately moistened, as a result of which the dirt is washed away even when very small amounts of water are used. The cleaning action of the water is strongly enhanced, as a result of which much less water is used for the same degree of fouling.

FIG. 2 shows a spray nozzle 14 with a rotating jet, whereby the jet exiting from nozzle 14 rotates about a central axis 15. A nozzle housing 16, which corresponds with nozzle housing 5 of FIG. 1, is provided with a water channel 17 and an air channel 18. An intermediate ring 19 is screwed onto nozzle housing 19, thus forming a mixing chamber 20. Mixing chamber 20 comprises an opening 21 to a chamber 22, which is formed by a holder 23 and intermediate ring 19. A rotating member 24 is provided in chamber 22, which member comprises a wear-resistant part 25, which is supported in an opening of holder 23. Rotating member 24 is capable of rotation about a central axis 26, and when member 24 rolls on the inner wall of holder 23 whilst the wear-resistant part is supported in the opening of holder 23, central axis 26 will rotate about the central axis 15 of nozzle 14 with a spraying angle 27. Rotating member 24 and wear-resistant part 26 are provided with a spray channel 28, and rotating member 24 is also provided with blades 29. Water flowing from opening; 21 into chamber 22 strikes against the blades 29, causing rotating member 24 to rotate about central axis 15 and about central axis 26. The water exits chamber 22 through the spray channel 28. It has become apparent that the amount of water required for causing rotating member 24 to rotate about its axis will be strongly reduced when water mixed with air is caused to exit from opening 21. A second advantage is that nozzle 14 can be blown dry in a simple manner, thus eliminating the problem of rotating member 24 caking onto holder 23 and nozzle 14 becoming unusable. This air support makes it possible to use nozzle 14 over a larger working area.

FIG. 3 shows spray nozzles 31 mounted on a rotatable arm 30, which arm 30 is mounted on a connecting block 2 by means of a rotatable coupling 32. The air and water connections are indicated by numerals 3 and 4 respectively. The interior of the unit actually functions as a mixing chamber 33, which—in view of its large dimensions—ensures an ideal mixing of water with compressed air. Numeral 34 indicates the axis of rotation of arm 30.

FIG. 4 diagrammatically shows a device according to the invention, which comprises a water source 35 and an air source 36. Water is supplied to a mixing chamber 39 by means of a pump 37 and a pressure control valve 38, whilst pressurized air is likewise carried to mixing chamber 39 via a pump 40 and a pressure control valve control valve 41. Furthermore a spray nozzle 42 is provided, which unlike the situation shown in the drawings—is disposed in a wall of mixing chamber 39. Nozzle 42 is accommodated in a separate housing 43, so that this is a closed system, wherein water can be reused and contamination of the surrounding area by the spray of water droplets from nozzle 42 is not possible.

FIG. 5 is a larger-scale view of the detail shown in the box of FIG. 4.

FIG. 6 shows a bulb re-washing machine 44, in which contaminations in the form of loose earth or sand are removed from bulbs B, for example tulip bulbs, hyacinth bulbs and the like, by washing said bulbs with water. Bulbs B are placed on a screen belt 45 via a chute, screen belt 45 is passed over pulleys 46, which are driven by a drive unit 47. The velocity of the screen belt 45 can be controlled steplessly, it will for example amount to 5 m/min. The velocity is set in such a manner that one to three layers of bulbs B are present on the belt, depending on the type of bulbs (dimensions). The layer of bulbs must not be much thicker than 0.05 m, in order to ensure a proper discharge of dirt by spraying. At the end of screen belt 45 the cleaned bulbs 48 are caught in a container.

Three rows of respectively two spray nozzles 1 according to FIG. 1 and one row of two arms 30 comprising spray nozzles 31 according to FIG. 3 are disposed under a cover 49 above screen belt 45, which is about 1 m wide, which spray nozzles spray in the direction of screen belt 45. The distance between the nozzles and screen belt 45 is about 0.20-0.30 m. A receptacle 50 is disposed under screen belt 45, in which the spray medium and the washed-off dirt are caught and discharged via a drain D.

Nozzles 1 and 31 are connected to an air pipe 51 and a water pipe 52. Air pipe 51 is connected to a pressure vessel 55 via an electrically controlled valve 53 and an adjustable pressure reducing valve 54. Pressure vessel 55 is maintained at a pressure set in a pressure switch 56 by means of a compressor 57. Pressure vessel 55 is furthermore fitted with a manometer 58. Water pipe 52 is connected to a pressurization unit 60 via an electrically controlled valve 59. Pressurization unit 60 is connected to a water supply C and may be set to various pressure values in a manner which is known per se.

The water consumption at water supply C is about 900 3500 litres per hour when a water pressure of 4 8 bar is used and an air pressure of likewise 4-8 bar and the consumption of air is 1.5-2³. In that case the washing capacity of the device will be 10 m³ of bulbs per hour at a belt velocity of 5 m/min. The various components of the bulb re-washing machine 44 are controlled from a control box 61. The air pressure in pipe 51 is set manually by means of adjustable pressure reducing valve 54, and the water pressure in pipe 52 may be set by means of a control valve (not shown) in pressurization unit 60.

When spraying is carried out with air support very fine droplets are formed at nozzles 1 and 31, as a result of which all bulbs are properly moistened and a flow of water is created on the bulbs. It has become apparent thereby that it is not necessary for the bulbs to be hit directly by a jet of water from nozzles 1 and 31 in order to create a flow of water discharging the dirt. The atomized fine droplets fall on the bulbs to be cleaned and transport the dirt to receptacle 50. Since the water is mixed with air, the jet of water being squirted from the nozzle orifice is not hard, so that no damage will be caused to bulbs B, not even to the bulbs that are passed right under nozzles 1 and 31.

The pressure of the water and of the air can be varied by adjusting the valves, which makes it possible to adapt the cleaning operation to the type of dirt, for example the soil type, and the amount of dirt to be removed.

Besides the embodiment shown herein it is also possible to catch the water being discharged at drain B in a container having a capacity of for example 2-3 m³, and to recirculate the water. In that case the earth or the other dirt being washed off the bulbs will remain behind in the tank as sediment.

In another embodiment of the machine spray nozzles 1 and 31 may be mounted on rotating arms, as a result of which the bulbs present on screen belt 45 will be sprayed from a short distance, which further enhances the cleaning effect.

Minor adaptations will make the bulb re-washing machine shown in FIG. 6 suitable for cleaning/washing other products in the agricultural sector as well, such as carrots, leek, celery and the like, and also for potatoes, for example. All these products must be made ready for consumption by washing, whereby inter alia dirt is removed from the products and no damage must be caused to the products.

FIG. 7 is a plan view of a detail of a leek washing machine, showing in particular the location at which the roots are cleaned. The Figure shows a toothed belt 62 with a tooth pitch of 5 cm, which is capable of movement in direction of transport V. Leeks 63 are present on the toothed belt, whereby they may be locally clamped (in a manner not shown) between toothed belt 62 and a conveyor belt 64 running above said toothed belt. Leeks 63 pushed with their roots against a stop plate, which is done manually or possibly by means of a pressure roller. The roots, which are 0.06 m long, are cut from the leeks 63 by mechanical means, and two to four bracts are removed. The capacity of the leek washing machine is about 1.2 tonnes of leek per hour, the velocity of the belt in the direction of transport V is about 5 m/min.

During this automatic process the contaminations, such as earth, are washed off the leeks with water. This water is contaminated with the washed-off earth and with juices being exuded by the plant, it may not be discharged into the surface water just like that, which is why it is caught. In addition to that the water and the discharging cost money. In order to keep the water consumption as low as possible, nozzles 1 connected to an air pipe 65 and a water pipe 66 are used. Nozzles 1 correspond with the nozzles shown in FIG. 1. When nozzles 1 are also provided with an air supply, the water consumption in the leek washing machine is reduced from 15,000 l/hour to 300 l/hour when using a water pressure of 4-8 bar distributed over six nozzles 1. The required amount of air is 1,500 l/min when using an air pressure of 4-8 bar. Since the jet produced by nozzle 1 is greatly mixed with air, said jet will be soft and the leeks will not be damaged.

FIG. 9 is a diagrammatic sectional view of a carwash 67 according to the invention, wherein a passenger car 68 is being cleaned by spray nozzles 1 according to FIG. 1, which are disposed at various angles in the ceiling and in the side walls of the carwash. The water saving may even be a more important factor with carwashes, since they use the more expensive osmosis water, which does not leave behind any water stains on the car paint. According to the invention the water-based car paint is additionally spared.

FIG. 10 shows a dishwasher 69, which constitutes a washing space 72 comprising a cabinet 70 and a door 71. Objects to be cleaned are placed in washing space 72 in a manner known per se. The dishwasher furthermore comprises all the other components which are known for such a machine, in so far as they are not described as being different hereafter.

In the illustrated embodiment a rotatable arm 30 fitted with spray nozzles 31 is shown at the bottom of washing space 72, which arm is capable of movement about an axis, as is shown in FIG. 3. Rotatable arm 30 fitted with spray nozzles 31 is connected to a water pipe 73 and to an air pipe 74. Water and air being supplied mix inside arm 30, and are squirted, in the manner already indicated above, from the orifices of the rotatable arm 30 fitted with nozzles 31, as a result of which a finely divided spray is formed. The amount of water being used for forming said spray is considerably lower than usual, since the droplets being formed are much smaller as a result of the mixing of water and air, so that the objects to be cleaned are moistened more adequately while using less water.

In accordance with another embodiment of the invention rotatable arm 30 may also be fitted with spray nozzles which correspond with the spray nozzle 1 shown in FIG. 1.

Spray nozzles 1 are mounted at the top of washing space 72, which nozzles correspond with the spray nozzles shown in FIG. 1. Said nozzles are connected, in a manner already indicated above, to a water supply and to an air supply by means of a water pipe 75 and an air pipe 76. Besides the illustrated embodiment comprising the washing space 72 at the bottom, a rotatable arm fitted with nozzles 31, and fixed nozzles at the top, also other embodiments are possible, wherein all nozzles are fixed, or wherein all nozzles are mounted on rotatable arms, whilst also intermediate forms are possible, depending on the desired washing result and the dimensions of the washing space 72.

A drain 77 is provided at the bottom of washing space 72, which drain is connected to a pump (not shown) comprising a screen, by means of which the washing water is pumped into water pipes 73 and 75, causing said washing to circulate. Since the nozzles operate with support air, in order to obtain a fine spray, the nozzle orifices (see FIG. 1) are relatively large, so that there will be no clogging and the screen present at the pump may be relatively coarse.

A breather duct 78 is provided at the top of washing space 72, through which the air supplied via the nozzles can exit the washing space again. This breather channel may be connected, in a manner not shown, to the intake of the compressor (not shown), as a result of which air pipes 74 and 76 are supplied with air, so that there will be recirculation of the air. In addition to using air for atomizing the water into extra fine droplets, it is also possible to use the air supply when no water is being supplied. As a result of this the objects present in washing space 72 will be dried extra quickly.

In one preferred embodiment the dishwasher only comprises spray nozzles 1 according to the invention in door 71.

FIG. 11 shows a tumbler washing machine 79 comprising a housing 80 provided with a door 81. Disposed within housing 80 is a tub 82, in which a rotating drum 83 provided with perforations is present. The inside of rotating drum 83 forms a washing space 84. Tub 82 and rotating drum 83 may contain an amount of water, whereby the water level is sufficiently high for immersing the laundry present in drum 83. Rotating drum 83 is attached to rotating shaft 85, which runs in bearings 86, and which is provided with a pulley 87, by means of which said shaft can be driven. Tumbler washing machine 79 furthermore comprises all the other components which are known for such a machine, in so far as they are not described as being different hereafter.

Spray nozzles 1 corresponding with the nozzles shown in FIG. 1 are mounted on the inside of drum 83. Nozzles 1 are connected to a pump 91 via a water pipe 88, a connecting block 89 and a water pipe 90. Spray nozzles 1 are also connected to a compressor 94 via an air pipe 92, connecting block 89 and air pipe 93. Mounting air supported nozzles 1 makes it possible to produce a fine spray therein, which moistens the laundry in an excellent manner, which enhances the washing effect. Pump 91 is connected to tub 82 via a drain 95, as a result of which the water can circulate via nozzles 1. Compressor 94 is also connected to tub 82 via an exhaust opening 96, as a result of which of which the air being released by nozzles 1 need to exit housing 80.

Various embodiments of connecting block 89 are possible. According to a first embodiment of connecting block 89, pipes 92 and 88 in rotating drum 83 are connected to corresponding pipes 93 and 90 at all times, whereby nozzles 1 attempt to squirt out water constantly, even if they partly blocked by laundry or water present in the drum. According to a second embodiment of connecting block 89 only the air pipes 93 and 92 are in communication with each other at all times, whereby the air exiting from nozzle 1 into the water when said nozzle is submerged will cause additional stirring and produce an additional washing effect, whilst the capacity of pump 91 may be smaller. According to a third embodiment of connecting block 89 only the pipes 92 and 88 of the nozzles 1 present above the laundry are connected to pipes 93 and 90. In this manner a spray is produced by nozzles 1 by using a pump 91 and a compressor 94 which have a relatively small capacity. This atomization of the washing water provides an improved washing effect.

By using nozzles 1 an atmosphere of minute droplets is produced in washing space 72 during washing, thus providing an improved washing effect. When this is done by means of air-supported nozzles, said minute droplets are produced at a lower water flow and with relatively large nozzle orifices, as a result of which recirculation of the washing water is possible without clogging. In order to prevent clogging or caking up of said orifices control means may turn on or maintain the air flow through nozzles 1 after the washing operation has been completed, so that contaminations and water are blown out of the nozzles.

In another simple embodiment of the washing machine according to the invention the nozzles are mounted in the door.

Another embodiment of the invention (not shown) consists of the use of the air-supported nozzle in a shower, whereby the cleaning and dirt-discharging effect is retained at a lower water consumption. Such nozzles may also be suitably used in other situations, where the use of water must be limited or where the water is caught in order to be reused in the above-described carwashes. The embodiments which have been discussed in the various examples may be used in various combinations thereof, whereby it becomes apparent in every instance that the water consumption can be strongly reduced by carrying out the cleaning and washing operations with nozzles which are suitable for a mixture of air and water.

In one embodiment, a method for cleaning a dirty surface by squirting water in a spray of droplets against the dirty surface to be cleaned includes the steps of mixing water and air under pressure in a nozzle device having coaxial bores, said nozzle having an upstream portion where the water and air under pressure are mixed to obtain a pressure for said mixture higher than the pressure outside the nozzle device; passing said pressurized mixture of air and water to a downstream fluid port portion of said nozzle device which is narrower than said upstream portion; squirting said spray against the dirty surface to be cleaned; and cleaning the dirty surface with said spray.

In one or more of the embodiments described herein, the surface to be cleaned is soft surfaces and wherein a range of water pressure and a range of air pressure measured as an overpressure relative to the water pressure are selected from the following groups (i) to (iii):

(i) water pressure from 2.8 to 4.2 bar and air pressure from 6.5 to 9.5 bar;

(ii) water pressure from 4 to 6.2 bar and air pressure from 6.5 to 9.5 bar; and

(iii) water pressure from 6 to 10 bar and air pressure from 6.5 to 9.5 bar.

In one or more of the embodiments described herein, an end wall of said upstream portion makes a right angle with respect to a side wall of said narrower downstream fluid port portion. In another embodiment, the water is squirted against the surface in a spray of droplets, from a distance which is smaller than a distance at which the water becomes turbulent downstream of the nozzle.

In one or more of the embodiments described herein, the method includes attaching a rotating member to the nozzle device and rotating the rotating member to manipulate a direction of the spray. In another embodiment, the method further includes flowing the mixture through the rotating member, wherein the rotating member is coupled to the downstream fluid port. In yet another embodiment, the method further includes impacting a plurality of blades coupled to the rotating member with the mixture thereby rotating the rotating member, wherein the blades extend radially outward from a central axis of the rotating member. In yet another embodiment, the method further includes resisting wear between the rotating member and the nozzle with a wear-resistant part proximate the downstream fluid port.

In one or more of the embodiments described herein, the method further includes flowing the water and air into the nozzle device through a nozzle housing having a central water bore and a plurality of air bores located around the central water bore. In another embodiment, the coaxial bores are formed by a terminal end of the central water bore and the upstream portion.

In one or more of the embodiments described herein, the fluid port leads to a second chamber and wherein the spray of droplets is squirted against the dirty surface downstream of the second chamber.

In one or more of the embodiments described herein, the air pressure is at least 1 bar. In another embodiment, the air pressure can be regulated.

The invention is not limited to the preferred variants discussed in the Figures, it also extends to other variants that fall within the scope of the invention.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. A method for cleaning a dirty surface by squirting water in a spray of droplets against the dirty surface to be cleaned comprising the steps of: flowing a liquid through a central bore of a nozzle housing; flowing a gas through a plurality of gas channels formed in the nozzle housing radially around the central bore; mixing the liquid with the gas in a mixing chamber, wherein the mixing chamber has coaxial bore portion formed by a terminal end of the central bore and an upstream portion of a nozzle; forming a mixture of the gas and liquid having a pressure higher than the pressure outside of the nozzle; flowing the mixture through an exit orifice of the nozzle, wherein the exit orifice has a diameter smaller than the diameter of the upstream portion; squirting the mixture against the dirty surface; and cleaning the dirty surface.
 2. The method of claim 1, further comprising attaching a rotating member to the nozzle and rotating the rotating member to manipulate a direction of the mixture engaging the dirty surface.
 3. The method of claim 2, further comprising flowing the mixture through the rotating member, wherein the rotating member is coupled to a holder coupled to the nozzle.
 4. The method of claim 3, further comprising impacting one or more blades coupled to the rotating member with the mixture thereby rotating the rotating member, wherein the blades extend radially outward from a central axis of the rotating member.
 5. A method for cleaning a dirty surface by squirting water in a spray of droplets against the dirty surface to be cleaned comprising the steps of: mixing water and air under pressure in a nozzle device having coaxial bores, said nozzle having an upstream portion where the water and air under pressure are mixed to obtain a pressure for said mixture higher than the pressure outside the nozzle device; passing said pressurized mixture of air and water to a downstream fluid port portion of said nozzle device which is narrower than said upstream portion; squirting said spray against the dirty surface to be cleaned; and cleaning the dirty surface with said spray.
 6. The method of claim 5, wherein pressurized water having a water pressure is supplied to said upstream portion of the nozzle device.
 7. The method of claim 6, wherein the water pressure can be regulated.
 8. The method of claim 5, wherein the spray of droplets exits said nozzle from said fluid port and is squirted against the dirty surface downstream of the nozzle.
 9. The method of claim 5, wherein the air pressure and the water pressure are set to a ratio ranging between 2:1 and 1:2, respectively.
 10. The method of claim 5, wherein the water is squirted against the surface in a spray of droplets, from a distance which is smaller than a distance at which the water becomes turbulent downstream of the nozzle due to lack of impetus.
 11. The method of claim 5, wherein the surface to be cleaned is a surface of flower bulbs, flower tubers or perennial plants and wherein a range of water pressure and a range of air pressure measured as an overpressure relative to the water pressure are selected from the following groups (i) to (v): (i) water pressure from 0.5 to 1.5 bar and air pressure from 8 to 8.5 bar; (ii) water pressure from 1.5 to 3 bar and air pressure from 7.5 to 8 bar; (iii) water pressure from 2.8 to 4.2 bar and air pressure from 5.5 to 6 bar; (iv) water pressure from 4 to 6.2 bar and air pressure from 5 to 5.5 bar; and (v) water pressure from 6 to 10 bar and air pressure from 3.5 to 6.5 bar.
 12. The method of claim 5, wherein the surface to be cleaned is a surface of soft fruit, and wherein a range of water pressure and a range of air pressure measured as an overpressure relative to the water pressure are selected from the following groups (i) to (ii): (i) water pressure from 0 to 0.5 bar and air pressure from 1.5 to 2.5 bar; and (ii) water pressure from 0.5 to 1.5 and air pressure from 1.5 to 2.5 bar.
 13. The method of claim 5, wherein the surface to be cleaned is a surface of medium hard crops, and wherein a range of water pressure and a range of air pressure measured as an overpressure relative to the water pressure are selected from the following groups (i) to (iii): (i) water pressure from 2.8 to 4.2 bar and air pressure from 6.5 to 9.5 bar; (ii) water pressure from 4 to 6.2 bar and air pressure from 6.5 to 9.5 bar; and (iii) water pressure from 6 to 10 bar and air pressure from 6.5 to 9.5 bar.
 14. The method of claim 5, wherein the surface to be cleaned is a surface of hard crops, and wherein a range of water pressure and a range of air pressure measured as an overpressure relative to the water pressure are selected from the following groups (i) to (iii): (i) water pressure from 2.8 to 4.2 bar and air pressure from 9.5 to 20 bar; (ii) water pressure from 4 to 6.2 bar and air pressure from 9.5 to 20 bar; and (iii) water pressure from 6 to 10 bar and air pressure from 9.5 to 20 bar.
 15. The method of claim 5, wherein the surface to be cleaned is sugar beets, beetroots or potatoes, or the products stemming therefrom, potato chips, pulp and cattle fodder products and wherein the water pressure is between 6 and 10 bar and the air pressure has an overpressure of 4.0 to 20 bar relative to said water pressure.
 16. The method of claim 5, wherein the surface to be cleaned is a surface of roads, and wherein the water pressure is between 6 and 10 bar and the air pressure has an overpressure of 7 to 20 bar relative to said water pressure.
 17. The method of claim 5, wherein the surface to be cleaned is vehicles, passenger cars in a car wash; or trains, buses or lorries in special washing facilities, and wherein the water pressure is between 0.5 and 1.5 bar and the air pressure has an overpressure of 2.5 to 6 bar relative to said water pressure.
 18. The method of claim 5, wherein the surface to be cleaned is a surface of crockery, cutlery in a dishwasher, or machines or tools in an industrial washing-up machine, and wherein the water pressure is between 0.5 and 1.5 bar and the air pressure has an overpressure of 4.5 to 8 bar relative to said water pressure.
 19. The method of claim 5, wherein the surface to be cleaned is a surface of persons, and wherein a range of water pressure and a range of air pressure measured as an overpressure, relative to the water pressure are selected from the following groups (i) to (iii): (i) water pressure from 0.5 to 1.5 bar and air pressure from 1.5 to 5; and (ii) water pressure from 1.5 to 3 bar and air pressure from 1.5 to
 5. 20. The method of claim 5, wherein the surface to be cleaned is hard surfaces, and wherein the water pressure is between 6 and 10 bar and the air pressure has an overpressure of 9.5 to 20 bar relative to said water pressure. 